I was a panelist on an MSNBC show during the noon hour of December 14.

When the show began, we had information about a school shooting in Connecticut.

We believed there were three people hospitalized with non-life-threatening injuries and a gunman who had committed suicide.

Scary stuff, but probably a story that would occupy our attention for the proverbial fifteen minutes.

But by the end of the hour, we’d heard reports that at least eighteen children under the age of 10 had been murdered in cold blood as they huddled in their classrooms.

It was a brutal hour, and one I’ll never forget. We had come to one of those moments by which we measure the end of an era: before the misery, grief and terror of this event, and after.

Even as the initial reports came in, those of us on the set called for action. We didn’t quite know what had happened, but we knew it was awful.

Something must be done!As the details of Adam Lanza’s murderous spree became clearer, many more Americans took up that call. In the first seventy-two hours after the massacre, 150,000 people signed a petition on the White House website calling for legislation limiting gun access.

No previous topic on the site had ever received so much support. Something must be done! During his remarks in Newtown on that Sunday evening, President Obama also spoke of the need to act.

“In the coming weeks,” he said, “I will use whatever power this office holds to engage my fellow citizens, from law enforcement to mental health professionals to parents and educators, in an effort aimed at preventing more tragedies like this.”

Though he declined to offer any policy specifics, it was clear the president also felt: something must be done! This is because the Newtown murders were not just tragic; they were an act of terrorism.

The slain first-graders and their teachers were not targeted because of their national identity, as were the victims of the 9/11 attacks. They were not murdered because of their race, as was the case in the decades of unchecked American lynchings.

They were not killed because of their religious beliefs, like the Sikh victims of a mass shooting in Wisconsin just a few months back. In fact, their undisputed innocence and relative privilege are part of what makes their deaths so horrifying — so terrorizing.

It is also what makes me nervous about the calls for action that are on everyone’s lips, including mine. After 9/11, we were caught in a state of national post-traumatic stress. We not only mourned having lost so many; we were terrified at the loss of our sense of security.

On September 10, 2001, we knew we lived in a dangerous world. But we were Americans, and some things just don’t happen here… until they do. On December 13, 2012, we knew we lived in a country where thousands of people are murdered by guns — 30,000 in 2011 alone — but we thought young children attending schools in prosperous, peaceful communities were immune. Some things just don’t happen there.

Until they do. And this is the aspect of the tragedy that makes it so terrifying. It undermines our belief that there is a safe place to be, to live, to send our kids to school. It is a bloody beacon of our inherent vulnerability. Nothing is harder to bear than that collective realization, so we feel we must act. While I agree with the need for action, I also urge us to reflect before we act. Remember what we did after 9/11?

We let government officials with their own agendas shape our ill-defined enemies into specific targets, some of which had no connection to the attacks.

In our terror, far too many surrendered civil liberties by supporting the Patriot Act, ran our national economy aground by cheering the war in Afghanistan, and damaged our status in the world by pushing “preemptive” aggression in Iraq.

If we’re not careful, we could end up repeating these mistakes of trauma-laden, terror-driven policy-making.

Yes, we need common-sense gun legislation. No, we do not need a national registry of those with mental illnesses.

Privacy and medical confidentiality must be protected, but that is unlikely to happen in an environment where the public becomes convinced there’s a strong correlation between mental illness and gun violence, even if that link is tenuous or false.

Yes, we need to address the pervasive violence in our communities. No, we do not need to limit or censor rap music, video games or violent films. We can certainly stop supporting violence with our consumer dollars, but the impulse toward censorship tends to have more deleterious effects than positive ones.

I’m not suggesting we do nothing. I’m suggesting that we recognize our current state of emotional trauma and act with caution, lest we worsen the very problems we hope to ameliorate. No modern thinker has contributed as much to our understanding of the inscrutable realities of evil and terror as Hannah Arendt.

Writing as a German Jew in the aftermath of the Holocaust, Arendt had a unique proximity to existential vulnerability. Yet her observation of the Adolf Eichmann trial produced not a polemic on the need to hold a small group of men responsible for their crimes, but rather an insight into the “banality of evil.”

“I was struck by a manifest shallowness in the doer which made it impossible to trace the incontestable evil of his deeds to any deeper level of roots or motives,” she later wrote in The New Yorker. “The deeds were monstrous, but the doer…was quite ordinary, commonplace, and neither monstrous nor demonic.”

This is the insight we must cling to. Evil can emerge from routine actions, especially when they’re motivated by fear and enacted in a haze of terror. Those young lives were cut short by guns that we allow to circulate legally. But nothing we do will bring the children back or ease our vulnerability. Yes, we must act.

But we must act deliberately, or we risk compounding the evil we hope to eradicate.

Melissa Harris-Perry is professor of political science at Tulane University, where she is founding director of the Project on Gender, Race, and Politics in the South. She is the author of Sister Citizen: Shame, Stereotypes, and Black Women in America, and a contributor to MSNBC.